In der Hoffnung, dass möglicherweise auch der eine oder andere Entwickler hier mitliest, gibt es diesen Kommentar auf englisch, die Community möge mir Vergeben...
Presumably in order not to have to run constantly upstairs and downstairs there are probably the transitions between the locomotives. These can be opened fortunately. However, locomotive drivers all seem to be so fat that they can not pass through the crossings. From this point of view, it may not be stupid that the way from one locomotive to the other leads just over the stairs ...